Planetary Orbits Elliptical

We have all seen the planetary model of our solar system since our school days. The planets are shown to revolve in a nice circular path, forming concentric rings, with the sun sitting smack-dab in the centre. While this vision of planets following a nice circular path around the Sun looks neat and tidy for a school project, in reality, things aren't that simple. The planets in our solar system don't really revolve in perfectly circular orbits. Instead, they generally have a stretched version of a circle, which is technically called an ellipse. How stretched you'd ask? Well, that depends on the orbital eccentricity that the planets possess. Too much mathematics going over your head already? Well, let's get the basics down first! An ellipse is a symmetrically shaped closed oval. It has two points, called foci, which act as a combined centre for an ellipse. This ellipse has an important property called eccentricity. Simply put, eccentricity tells how much the ellipse deviates from the perfect circle. Mathematically, the value of eccentricity varies between zero and one, with zero representing a circle and one transforming into another shape, called a parabola. For planetary objects, when orbital eccentricity crosses 1, the planet no longer remains confined to the star, and it 'escapes' from its gravitational influence.